Approximately 1.7 million adults and children suffer a traumatic brain injury (TBI) each year in the United States. Of these, approximately 1.37 million are treated and released from an emergency department, 275,000 are hospitalized, and 52,000 die. Motor vehicle crashes (including motorcycle crashes) account for about 17 percent of these TBIs. Motorcycle crashes account for approximately 10 percent of all motor vehicle crash fatalities, even though motorcycles make up only 3 percent of all registered vehicles in the United States. Per mile traveled, motorcycle crashes are approximately 37 times more lethal than automobile crashes. Although sports injuries contribute to fatalities infrequently, the leading cause of death from sports-related injuries is traumatic brain injury. Sports and recreational activities contribute to about 21 percent of all traumatic brain injuries among American children and adolescents. There were an estimated 446,788 sports-related head injuries treated at U.S. hospital emergency rooms in 2009. The most prevalent sports in which traumatic brain injury occurs are, in order of prevalence, cycling, football, and baseball/softball.
A variety of protective helmets have been developed to protect a user against injury resulting from an impact to the head. For example, in the sports of football, hockey, and baseball, players typically don helmets during play to protect their head from catastrophic injury, which may result from an impact by another player, impact with the ground, ice or side of a hockey rink, impact of a baseball pitch hitting the head, or the like. Helmets typically include a rigid outer shell formed of hard plastic and interior padding of various forms, including specially designed multiple studs in football helmets, formed of vinyl, foam, polypropylene, or similar material that is suited to absorb energy mechanically by being compressed and/or bending.
Conventional helmets for motorcycle riding, sports and other activities have been shown to effectively protect against some injuries, such as skull fractures, but are significantly less effective at protecting against other types of TBI and chronic traumatic encephalopathy (CTE), For example, while conventional helmets often work well at dampening linear forces caused by impacts towards the center of the head, they typically do not adequately dampen angular accelerations—or “glancing blows”—to the head, which force the brain to rotate within the skull. These angular impacts can be just as damaging to the different parts of the brain and brainstem as direct impacts.
Therefore, it would be highly advantageous to have improved helmets for use in motorcycle and bicycle riding, sports, transportation, the military, and any other human endeavors where TBI and CTE is a concern. Ideally, such helmets would include improved shock absorption capabilities, which would help prevent or at least reduce TBI and CTE caused not only by direct impacts, but also by angular impacts, regardless of the direction from which they come from. Also ideally, such helmets would be low-weight, light, inexpensive, washable, and practical to wear. At least some of these objectives will be addressed by the embodiments described below.